Coaxial transmission line connecting or termination device



May 27, 1958 H. E. STRAUSS ET AL 2,836,547

COAXIAL TRANSMISSION LINE CONNECTING OR TERMINATION DEVICE Filed 0.0L 1, 1954 Mai/er v gghlit Z/Focxwzu United States Patent COAXIAL TRANSMISSION LINE CONNECTING 0R TERMINATION DEVICE Herbert E. Strauss, Philadelphia, Pa., and Daniel T. Rockwell, Merchantville, N. J., assignors to Radio Corporation of America, a corporation of Delaware Application October 1, 1954, Serial No. 459,664

The terminal years of the term of the patent to be granted has been disclaimed 2 Claims. (Cl. 174-75) The invention relates to an improved connection or terminal member particularly adapted to electrical transmission lines or cables of the coaxial type.

Ditficulty is experienced in providing adequate connections between coaxial cables, especially cables having a flexible outer conductor, and load devices coupled thereto. Such connections should be well insulated and protected from stress at the point where the cable is secured to the connector. The conductors should be protected from water or other liquids which would shortcireuit the electrical conductors within the connecting apparatus. Various connectors including soldered, bolted or wired connecting means are not completely satisfactory because normal operational stresses tend to break the electrical connections or conductors. In utilizing such connecting means other difliculties are also encountered. For example, when coaxial conductors are secured to connecting means by soldering great care must be exercised not to melt or burn thru the insulating material thereby injuring or short-circuiting the cable.

It is an object of the present invention to provide an improved coaxial cable terminating or connection device.

It is a further object to provide an improved solderless connecting means for coupling a coaxial cable into a shielded compartment.

Another object of this invention is to provide an improved coaxial cable fitting which minimizes strains on the electrical conductors and connection points.

Another object of this invention is to provide an improved coaxial cable fitting which adequately locks the cable to the fitting and protects the electrical connection points.

The foregoing and other objects and advantages are accomplished in accordance with the invention wherein a preferred embodiment comprises a coaxial fitting including a bushing apertured to receive the inner conductor and an exposed portion of the dielectric element of the cable, the bushing including an annular flange at one of its ends. The outer cable conductor braid wires are separated and held in position over and uniformly around the flange. The braid wires then are passed thru the hole in a first washer and clamped between the first washer and a second washer. A nut threaded to the bushing may provide the clamping pressure.

The invention will be described in greater detail by reference to the accompanying drawing, in which:

Figure 1 is an exploded perspective view of a preferred embodiment of the invention;

Figure 2 is a view partially cross-sectioned along a longitudinal axis of said preferred embodiment of the connector and cable of the invention in partially assembled relationship;

Figure 3 is a view partially cross-sectioned along a longitudinal axis of a modified preferred embodiment of the connector and cable of the invention in fully assembled relationship. 7

Similar reference characters are applied to similar elements throughout the drawing.

Referring to Figure 1, a flexible coaxial cable comprises an inner conductor 1, an outer preferably braided conductor 2, a flexible dielectric 3, of a material such as plastic or rubberized substance, disposed between the two conductors, and an outer insulating sheath 4 which surrounds the outer conductor 2.

The terminal structure according to the invention includes an externally threaded hollow bushing 5 apertured to form channel 11 so as to slide over an exposed portion of the outer surface of the flexible dielectric 3 of the cable. The bushing includes an annular flange 6 at one end thereof. Two washers, 7 and 8 are provided for the bushing 5, the hole in washer 8 being as large as or smaller than the hole in washer '7. The hole in washer 7 should be smaller than the peripheral diameter of the flange 6. For purposes of illustration, the hole in washer 8 is shown smaller than the hole in washer 7.

As illustrative of a typical manner in which the terminal structure may be utilized, a section of a wall or panel 10 is shown having an aperture 12 therein to receive the bushing 5, the aperture being of a diameter smaller than that of the flange 6.

The terminal may be assembled in the following manner. The outer sheath 4 of the cable is removed so as to expose a length of the outer conductor 2. Then, the outer conductor 2, which is in the form of a braid or a plurality of wires, is combed and fanned out exposing a portion of the dielectric 3 about twice as long as the bushing 5. A portion of the dielectric 3 is removed to expose suflicient length of the inner conductor 1 for electrical connection thereto.

The cable is then inserted thru the bushing channel 11 from the flanged end so that the dielectric 3 and the exposed end of the inner conductor 1 will extend therethru and beyond the bushing, thereby enabling an electrical connection to be made to the exposed length of inner conductor 1. The wires of the outer conductor 2 are bent over the outer surface of flange 6 and held adjacent to the outer surface of bushing 5, the wires being bent so that they will be uniformly distributed around the surface of the bushing. The washer 7 is then placed over the bushing and the braid members of the outer conductor 2 and pushed along the bushing until it presses the conductor wires into contact with the flange 6. The hole in washer 7 must be of suflicient size to permit the ready passage thereof over the braid members surrounding the bushing 5. The ends of the wires of conductor 2 extending thru the washer 7 are then bent outwardly, as shown in Figures 2 and 3. The second washer 8 is then placed on the bushing to clamp the outwardly extended outer conductor wires between the two washers.

As shown in Figure 3, the bushing 5 may be inserted thru an aperture 12 in a wall or panel. A nut 9 is threaded on the bushing and tightened so as to provide a firm and secure connection between the bushing, the outer conductor 2, the washers 7 and 8 and the panel. If desired, the ends of the outer conductor 2 may be trimmed even with the outside edge of the washers to present a neat appearance.

Any strain on the cable is uniformly distributed since the outer conductor braid members are uniformly distributed around the bushing 5. Electrical connection to the inner conductor 1 therefore is substantially free from strain on the cable.

Since there is insuificient space between the outer conductor braid 2 and the wall or panel 10, radio frequency leakage fields can not be developed.

The foregoing example provides a connection to a metal or conductive partition which may be grounded. If it is desired to connect the outer conductor 2 to other Patented May 27, 1958 f 2,836,647 v y I apparatus, the wall or panel may be of insulating material. A part of the untrimmed conductor 2 may be used for electrical connection or a connection lug 13 may be secured between the nut or the washer 8 and the partition, as shown in Figure 3. If desired, both the lug 13 and the end 14 of the inner conductor 1 may be formed for mechanical connections, in order to eliminate the necessity for soldering thereto.

If it is desired to omit the washer 8, the outer conductor ends could be secured between washer 7 and the wall or panel 10.

What we claim is:

1. A lead-through connector for a coaxial cable of the type having an inner conductor, dielectric means surrounding said inner conductor, and an outer conductor surrounding said dielectric means formed of a material which is capable of being deformed from its original cross-sectional configuration to one of substantially greater circumference comprising, in combination, an elongated cylindrical member having an aperture therethrough and being formed with an outwardly-extending flange at one end thereof and with external threads at the other end thereof; a pair of conductive washers which, when in operative position, are located on said elongated member, an end portion of said inner conductor and said dielectric means thereabout being adapted to pass through said aperture in said cylindrical member, and the corresponding end portion of said outer conductor of said cable being adapted to fit over said flange, through the aperture in the washer adjacent said flange, and between adjacent faces of said two washers; and a nut having internal threads engageable with the external threads on said elongated member.

2. In combination, a cable having an inner conductor,

dielectric means surrounding said inner conductor, and

an outer conductor that surrounds said dielectric means and that is formed of a material which is capable of being deformed from its original cross-sectional configuration to one of substantially greater circumference; first, second, and third annular members, each formed With an aperture through which end portions of said inner conductor and said dielectric means can pass, said annular members being arranged in the order named; said cable, when in position, having an end portion of said inner conductor and said dielectric means passing through said apertures in said members and having a corresponding end portion of said outer conductor positioned external of said first member, positioned between adjacent faces of said first and second members, positioned within said aperture in said second member, and positioned between adjacent faces of said second and third members; and clamping means for holding said cable and its components between said members in the position described, said clamping means including an elongated cylindrical member having an opening therein and through which said end portion of said inner conductor-land said dielectric means can pass, having an external diameter smaller'than that of said apertures in said second and third annular members, having external threads, and being secured at one end thereof to said first annular member, and said clamping means further including a nut having internal threads adapted to engage said external threads.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Aug. 5, 1953 

